As is widely known, in a manufacturing process of glass sheet products typified by a flat panel display, a solar cell, or the like, there has been developed a technology of performing processing and inspection while conveying glass sheets in vertical orientation.
Incidentally, in recent years, there has been an increasing demand for thinner glass sheets in order to reduce weight of the products or the like. For example, thin glass sheets having a sheet thickness of 300 μm or less have been mass-produced. Due to the fact described above, the following problems arise when the glass sheets are conveyed as described above.
Specifically, the glass sheet becomes more liable to be deformed as the glass sheet becomes thinner. Thus, when the thin glass sheet is conveyed in vertical orientation, for example, vibration is liable to occur due to air pressure difference between a front surface side and a back surface side of the glass sheet and a vibration amplitude is liable to be increased. As the vibration described above becomes more significant, the glass sheet becomes more liable to be broken through propagation of microcracks contained in the glass sheet. Further, when the vibration amplitude in the glass sheet is increased during inspection performed through use of an imaging device such as a camera, a region that is displaced in a sheet thickness direction of the glass sheet due to the vibration is liable to be located out of a focal point of the imaging device, thereby sometimes failing to perform accurate inspection of presence or absence of a defect. In view of the above, a technology for solving those problems is disclosed in JP 2009-236771 A.
In JP 2009-236771 A, there is disclosed a sheet member conveyance device including two gripping part groups each including a plurality of gripping parts arrayed away from one another along one of an upper edge portion and a lower edge portion of a glass sheet in vertical orientation, the gripping part groups being configured to grip the upper edge portion and the lower edge portion of the glass sheet to convey the glass sheet along a longitudinal direction of the edge portion, in which the gripping part groups are configured to apply a tensile force between the upper edge portion and the lower edge portion of the glass sheet under a state in which the upper edge portion and the lower edge portion of the glass sheet are gripped.
With the configuration described above, the tensile force can be applied to the glass sheet in the vertical direction during conveyance. Therefore, it is expected that the increase in vibration amplitude may be suppressed owing to the tensile force, and detection accuracy of a defect may be improved when the inspection is performed on the glass sheet through use of the above-mentioned device.